WASHINGTON — Embattled Rep. Trey Radel of Florida resigned Monday, a little more than two months after pleading guilty to misdemeanor cocaine possession.

Radel, 37, a Republican from Fort Myers, submitted a resignation letter to House Speaker John Boehner that took effect at 6:30 p.m.

"Unfortunately, some of my struggles had serious consequences," Radel said in his letter to Boehner. "While I have dealt with those issues on a personal level, it is my belief that professionally I cannot fully and effectively serve as a United States representative to the place I love and call home, Southwest Florida.

Radel, who was facing an ethics investigation, sent shorter resignation letters to Republican Gov. Rick Scott and Florida Secretary of State Ken Detzner. They will have to coordinate a special primary and general election to choose the next person to represent Florida's 19th District. A date has not been set.

"I believe that Trey is making the right decision for him and his family," Scott said in a statement. "I'm glad that he has sought help, and it's my hope he continues to put his attention on rehabilitation and his family."

A former conservative radio show host, Radel was caught buying $250 worth of cocaine on Oct. 29 at a Washington restaurant from an undercover federal law enforcement officer. He blamed alcohol abuse and returned to Capitol Hill this month after 28 days at a Naples, Fla., treatment center.

Radel's office will remain open to handle constituent issues but will be managed by the clerk of the House until Radel's successor is elected and sworn in, according to Radel's chief of staff, Dave Natonski.

Radel is believed to be the first sitting member of Congress charged with cocaine possession.

In an interview this month, he sounded optimistic he could overcome his troubles and continue to represent his Southwest Florida district.

"This is something I will continue to work on the rest of my life," he told reporters at the time. "I will take it one day at a time and, in doing so, I hope to rebuild and regain trust."

Radel had resisted calls from Scott and other Republicans to step aside. When he returned to work this month for the new legislative session, he began making amends with colleagues and apologized to them personally for his actions.

But after two weeks, it became clear things would not be easy for him. A House Ethics Committee investigation, launched in December, threatened to hang over his re-election campaign. Prominent Republicans in his district began signaling interest in his seat. And Radel had trouble winning over some Republicans who thought he should have resigned when he pleaded guilty.

"If he had asked my advice, I would have told him to do it the moment that he was (caught)," Rep. Trey Gowdy, R-S.C., a member of the House Ethics Committee, said Monday. "Frankly, if you have that in your life, you shouldn't run in the first place."

A number of Republicans had been eyeing the 19th Congressional District seat, including state Senate Majority Leader Lizbeth Benacquisto and Paige Kreegel, who finished third in last year's primary.

Former representative Connie Mack, who preceded Radel in Congress, had been considering running if Radel decided not to seek re-election.

"Trey's decision to resign from Congress was undoubtedly very difficult, but it was the right decision," Mack said in a statement Monday. "Now it's time for Southwest Florida to elect a new congressman who will be a tireless champion of our shared mainstream conservative values."

Mack's statement made no mention of his political plans, but he said the next representative from Southwest Florida should push for his "Penny Plan" to reduce federal spending. The proposal would cut a penny from every federal dollar spent.

The ethics investigation is expected to close now that Radel has left office and the panel no longer has jurisdiction over him.

Radel has described himself as a "hip-hop conservative" because of his appreciation for rap music. And he suggested that his Tea Party-supported push for limited government resonated with inner-city blacks rallying around the "fight-the-power" message championed by '80s rap groups such as Public Enemy, a Radel favorite.

He embraced social media, frequently posting sharp opinions and random observations on Twitter and other electronic forums older House members have been slower to use.

His support for reining in government, lowering taxes and cutting the deficit played well with the Republican core of his district. But he also showed a pragmatic streak, fighting for hundreds of millions of dollars for water projects designed to remove brackish water being carried from the Everglades and befouling local beaches.

Radel said this month that he wanted to continue that agenda, particularly his work on a water bill under negotiation in a House-Senate conference committee. He also mentioned his interest in immigration issues, notably on proposals to strengthen border security and increase visas issued to foreign high-tech workers.

He was blasted as a hypocrite after his arrest for voting in September to drug-test food stamp recipients. When asked about that vote following his guilty plea, Radel suggested that members of Congress should be tested for drugs.

In his letter to Boehner, Radel thanked the speaker for his "tremendous support and encouragement," and said it was an "honor" to serve the district.

He ended by expressing support for bipartisan solutions to the problems facing Congress.

"As an eternal optimist, I know there are great things in store for our country when we find ways to work together," he wrote. "Whether it is as a father, a husband, or in any future endeavor, I hope to contribute what I can to better our country."